Monito Del Monte: Microbiotheria - Physical Characteristics

species seeds mistletoe tree

The common name monito del monte is Spanish for "little monkey of the mountain." The "monkey" aspect of the common name derives from the animal's nearly furless, somewhat monkey-like hands and feet. Another local common name for the species is colocolo. The scientific name of this species has recently been changed to Dromiciops gliroides, and the species may be referred to as Dromiciops australis even in recent writing.

As with the other living New World marsupial orders, the single living species of Microbiotheria is a remnant with a more diverse past. The fossil record has revealed an extinct genus, Microbiotherium, with six known species, that thrived during the Oligocene and Miocene Epochs (thirty-four million years ago to five million years ago, for a period of thirty-nine million years). Today, D. gliroides represents an order with only a single living species.

An adult monito del monte's size is between a rat's and a squirrel's. The head-and-body length runs 3.3 to 5 inches (8.3 to 13 centimeters). The tail length is about the same, running 3.5 to 5 inches (9 to 13.2 centimeters), The adult body weight runs about a half ounce to just over one ounce (16.7 to 31.4 grams). The animal's coat of fur is fine, short and thick. The upper body pelt is brown, with several light gray patches or spots on the shoulders and rump. The face fur is gray, the large eyes encircled with prominent black rings. The belly fur is pale tan.

The tail is completely furred, except for a furless area, about an inch long (2.5 to 3 centimeters), on the underside, at the

MONITOS AND MISTLETOES

The thousand-or-so species of mistletoe are distributed over most of the world, including the moist temperate forests of southern South America. Mistletoes are hemiparasites, meaning partly parasitic. Although they have green leaves for photosynthesis, they live on tree branches and trunks, anchoring themselves and tapping into the wood to steal nutrients and water from the host tree. In most species of mistletoe, the seeds are spread by birds, which eat the seeds and defecate (DEF-uh-kate) them later while roosting. If they void the seeds while roosting on a tree branch, the seeds, covered with a gluey substance called viscin (VIS-in), are likely to stick to the branch and grow up to be mistletoes.

In an exception to the habit of birds being the main vectors, or transporters, for mistletoe species, the monito del monte feeds and disperses seeds of the mistletoe species Tristerix corymbosus. In fact, the little marsupial, as far as anyone knows, is the only disperser of the seeds of this mistletoe species. This was discovered by Guillermo Amico and Marcelo Aizen of the National University of Comahue, Argentina. During field studies, they came across numerous strings of mistletoe seeds sticking to the trunks of host trees. They were seeds of T. corymbosus, the fruits of which are green when ripe. Normally, green color in fruits indicates that they are not yet edible, so that fruit-eating birds will pass them up. The large number of T. corymbosus strings glued to tree trunks was also unusual, since birds defecate mistletoe species' seeds while roosting on tree branches. Only some of the seeds end up on branches and grow, and birds have no special ability to aim for tree trunks.

On the other hand, some mammal species consume ripe green fruit. That known fact and the sight of lots of mistletoe seeds on tree trunks indicated an arboreal, or tree-living, mammal as the seed-eater and disperser. Further searching and observing revealed that mammal to be the monito del monte. The species gorges on the mistletoe fruit. The animals peel the rinds off the fruit with their front paws, swallow the innards whole, seeds and all. Soon after a meal of mistletoefruits, the marsupial defecates almost all the seeds, undamaged by the animal's digestive system, in and on its foraging territory, which includes tree trunks and branches.

tip. The one-third of the tail closest to the body has the same sort of dense, woolly fur as the body, while the rest of the tail has straight, dark brown fur. The female's well-developed pouch is comfortably lined with light brown fur and has four nipples. The ears are moderately furred.

Young monitos del monte first live in their mother's pouch, then in the nest, and finally ride on her back while she looks for food.(Illustration by Michelle Meneghini. Reproduced by permission.)

As in many small marsupials, the snout is conical, cone-shaped, and tapering, but shorter than is usual among marsupials.

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